Small glitch here where the 'Aperture' and 'ISO Speed' are not aligned with the rest of the meta-data in the tooltip for a photograph. The default tooltip has not been customized.
Edit it and add an extra tab between those two fields. The font you're using must have slightly different widths.
(In the future, we'll be changing things here to use actual columns, but at the moment it works using tab positions where each line is independent of any other.)